Posted
by
michael
on Wednesday November 06, 2002 @12:09PM
from the stellar-attraction dept.

trotski writes "The Globe and Mail is running an article about the discovery of a magnetar star by Canadian astronomers. The star, named SGR 1806-20, is located 40,000 light-years from earth. This neutron star is one of only four magnetars ever discovered. Magnetars are characterized by their huge magnetic fields, billions of times stronger than any magnets on Earth. Apparently, if this star was located as far away as the moon, it could demag floppy disks and suck change right out of your pocket."

They explain it was detected by observing the effects the stars magnetic field has on charged particles. With a magnetic field of 10^15 gauss (vs 1-5 for the sun and the 10 - 50 for the Earth), it was mentioned that it won't just suck change out of your pocket, but rearrange the molecules in your body. Sounds like fun, doesn't it.

10^15 gauss is 10^11 Tesla. An MRI magnet (which is about the size of a large closet) puts out about 1.5 Tesla. The largest MRI magnet being proposed for use on humans is 8 Tesla, at the Ohio State University. This is still over 10 billion times smaller than 10^11 Tesla.

Just out of curiousity, where does that 100 billion Tesla number come from? I don't recall it from the article.

I ain't a physicist either an' ah don't spell too good but as Irecollect from here an there [maybe it was Babylon V],a neutron dense substance is impervious to a magnetic fields..In order to permeate a region filled with a given mass, itis necessary for the magnetic field to induce"domains"in a paramagnetic substance,[like from the latin ('pro'magnetic rah, rah, rah, etc)].In all the tiny crystals of metals where the electronic shellsmerge together & surge about like schools of tropical fishin a coral garden we see them setting up counte magneticfields that essentially linkthe field[lenz' law] to the otherside in a process called [what else] "connection"..Magnetomotive Force= Flux * Spacial Impermiabilitylook it up its the Ohms' law of 'Magnetics'..In a neutron star where the body is pure neutronium[Babylon V rah rah rah} it is difficult to set up domains.[hey if you know a way you'll make my day & the FBI will confiscate your PC] See, because when neutronsdecay, positive & negative particles emerge in preservation of the "Conservation of Charge Law" n[0] =e[-] + p [+] but I neverheard of anyone getting a magnetic moment out ofpure neutroniun...All you poor souls worryin' bout the neutron star singing your pants don't worry about it its only a 'gedankenexperiment'to see if you could follow an argument without being boggeddown in inconsequentials. Actually' all the star, is a burnt out cinder , you know solar pheonix reactions h+C => N[13?]etc Got no power. Further, graviton interaction with thermalmolecules would absorb heat until the planet shatteredto become confetti on the star's surface, but very cool..Knowledge is power, don't expect to find anything substantialon a page labeled nasa.gov. They got the power & you move the boxes. uh oh I think I just lost my benny pointsSPQR

Your eyes would be most likely accelerated at the same rate as the rest of your body, unless you were some how standing on your face on the surface of a very small, very cool, yet very massive star. Pretty bloody unlikely.

Iron, nickel and cobalt, actually. Couldn't tell you why. And for the record Canadian nickels, dimes, quarters, loonies and toonies (and even some of the later silver dollars, which were nickel) are all magnetic. Basically everything but pennies.

What's the deal with iron and magnets, anyway? Why just iron? Why's it so special?

Check out its location in the periodic table. See how it has an incomplete electron shell? The charges aren't balanced because the shell has some potential holes in it, so the atom has a charge. Similar metals also exhibit magnetism.

Uhh- I don't believe that just because an item is non-ferrous, it is not susceptible to magnetic fields. I do believe that the more intense a magnetic field is, the more likely it is to affect a myriad of other 'non-ferrous' items.

Try going near an MRI [howstuffworks.com] machine with change in your pocket. I made that mistake once, and it was tugging hard at the coins from across the room. >1 tesla magnetic fields need to be treated with respect - people can get seriously hurt if anything metallic gets brought into the room - they can get ripped out of your hand or pocket and will fly straight down the central bore where the patient is. I've heard stories of people being killed when someone walked into an MRI room with a pair of scissors in their pocket.

I've heard stories of people being killed when someone walked into an MRI room with a pair of scissors in their pocket.

My father works in a hospital as a pharmacist. He has told me a story about how someone walking by the room door with an oxygen tank was killed... the tank was on the opposite side of them and they were basically crushed under it. It's not necessarily the fact that the magnetic field strength is one tesla, it is because the field does not weaken much when you walk away from it.

I've dealt with magnets that are over one tesla (neodymium), and they only put a very very very small force on any american change i put right next to them.

It's not necessarily the fact that the magnetic field strength is one tesla, it is because the field does not weaken much when you walk away from it.

Request for information:
According to Biot-Savart's law [xrefer.com], as well as coming directly out of Maxwell's equations and Ampiere's theorem, the strength of a magnetic field is inversely proportional to the square of the distance from the conductor...

Or, in other words, magnetic field strength drops off as a square of the distance you travel away from it... so yes, it should weaken much when you walk away -- unless MRIs work in some drastically different way?

It also depends on how big the magnet is. For instance, I work with an 8 Tesla magnet, but it is actually only a uniform field over a very small distance (probably less than 2mm), and the field falls off quickly. There is a magnet at the Ohio State University Medical School that is also 8 Tesla, but has a considerably larger bore (big enough to fit a human body). This magnet is considerably more dangerous. It is so much larger that everything you are thinking of scales, but at a much 'slower' rate. In other words, you have to get much farther away from the big magnet than you do from the little one to escape magnetic field strengths strong enough to erase credit cards, even though both magnets have the same magnetic field.

Size does matter;p. So it is important to point out that a small effective sphere of 8T is much less impressive than a gigantic one of lesser field strength. The Earth relatively "weak" magnetic field has an impressively large area of efficacy that HAMs can attest to. HAARP and the aurora borealis [allanstime.com] show how large scale weak fields can, if you were to find the total potential the field provides rather than its peak strength, do huge tasks.

Is that the best way to explain it? "if you were to summate all the potential the field provides" rather than look at peak values?

I have to disagree about which is more dangerous. 8 Tesla can kill you from a great distance if you have a pacemaker, and can also crush you to death if you come between it and a large metal object that somehow gets free- it happens. Your credit cards will be erased from a several meters away.

None of these things will happen in the Earth's magnetic field. It is very dilute, and much weaker than 8 Tesla. It won't kill you, though it is responsible for the phenomena mentioned.

Read up on the near field and the far field. It is the far field that falls off to inversely to the square of the distance. The near field size will depend on the size of the magnetic and the strength of the magnetic field.

The story you are referring to is this [go.com] one.
And an 16 gauss field can make a frog levitate!
See here [sci.kun.nl]
Magnets are really the next frontier of technology, we just spend too much money using them to throw particles around rather than using the actual natural properties of them.
--ngoy

Field effect is fairly well understood and things don't have to be magnetic to be affected by magnetic field, as show by the frog and the water.

I find the use of a superconductor (you can induce a charge around this solenoid and the charge will remain forever creating a permanent magnetic field so long as the superconducting material is kept cold enough, so no perpetual machines for you mad quack scientists) quite impressive. Now to pin point a superconductors that operates at a reasonable temperature, not 138K@1ATM.

The world record Tc of 138 K is now held by a thallium-doped, mercuric-cuprate comprised of the elements Mercury, Thallium, Barium, Calcium, Copper and Oxygen. The Tc of this ceramic superconductor was confirmed by Dr. Ron Goldfarb at the National Institute of Standards and Technology-Colorado in February of 1994. Under extreme pressure its Tc can be coaxed up even higher - approximately 25 to 30 degrees more at 300,000 atmospheres.

Anyways, most of these super X men magneto stories are urban legends brought into the world by the same pseudo science types that concoct warp nacelles and wormholes, I hope these are possible and am unable to prove or disprove these constructs. I hate to piss on the parade, people, let's start with more plausible things. But someone recently was crushed an oxygen tank in a hospital near an MRI (which is an application of NMR, nuclear magnetic resonance imaging) because the tank wasn't properly secured against the wall. I don't buy the scissors in the pocket bull. Because an 8 Tesla field would make short work of and kill people with pacemakers, so because of this (2 million Americans have pacemakers so it's not exceedingly rare) they post all sorts warnings all over the damn place where high field magnets are stored. Also there are permittivity issues; "space" is a good insulator for fields, electrical gravitational just about any disturbance the field tends to rapidly loose strength. So all you Dr. Evil types thinking of ways to abuse a 16 Tesla field think again.

Seriously though, would be scientists and sky watchers x-filers conspiracy theorists and general bullshit artists could do so much better for their cause if they were better educated. In a network of words, rife with information, a whole internetwork that sprung forth from intellectual endeavors, it amazes me the levels of pseudo-science, quackery, pseudo-intellectualism bullshit and other assorted trash that ended up turning a potentially awesome source of information a better source of misinformation. Would be genius who are kings in their own minds are allowed to pump trash at an alarming rate and the hallucinate hoards of drones bleating like sheeple to lick up every last word of quack science they promulgate.

Cobalt and nickel are magnetic, as well as Iron. There are apparently ceramics and other materials that have ordered magnetic. Ordered is an important distinction. In general, ordered magnetic materials are mostly based around the transition metals (there are others besides Co, Ni and Fe), and the rare earths. All rather heavy.

If you want to use the term "magnetic" to mean something that responds to a magnetic field, I would love to see a material that isn't magnetic.

ferromagnetism - Iron, nickel, cobalt and some of the rare earths (gadolinium, dysprosium) exhibit a unique magnetic behavior which is called ferromagnetism because iron (ferric) is the most common and most dramatic example. Ferromagnetic materials exhibit a long-range ordering phenomenon at the atomic level which causes the unpaired electron spins to line up parallel with each other in a region called a domain. Ferromagnets will tend to stay magnetized to some extent after being subjected to an external magnetic field. This tendency to "remember their magnetic history" is called hysteresis.

antiferromagnetic Applied to a ferromagnetic (in the wide sense) substance in which the magnetic lattices are magnetized in exactly equal and opposite directions. Such a substance does not have an external magnetic field in its pure form, but a distorted lattice may result in a parasitic magnetization. This occurs below a certain temperature, called the Néel temperature, when an ordered array of atomic magnetic moments spontaneously forms in which alternate moments have opposite directions. There is therefore no net resultant magnetic moment in the absence of an applied field. In manganese fluoride, for example, this antiparallel arrangement occurs below a Néel temperature of 72 K. Below this temperature the spontaneous ordering opposes the normal tendency of the magnetic moments to align with the applied field. Above the Néel temperature the substance is paramagnetic.

ferrimagnetism a type of magnetism exhibited by the ferrites [[defined as: A member of a class of mixed oxides MO.Fe2O3, where M is a metal such as cobalt, manganese, nickel, or zinc. The ferrites are ceramic materials that show either ferrimagnetism or ferromagnetism, but are not electrical conductors. For this reason they are used in high-frequency circuits as magnetic cores]]. In these materials the magnetic moments of adjacent ions are antiparallel and of unequal strength, or the number of magnetic moments in one direction is greater than those in the opposite direction. By suitable choice of rare-earth ions in the ferrite lattices it is possible to design ferrimagnetic substances with specific magnetizations for use in electronic components

paramagnetism the atoms or molecules of the substance have net orbital or spin magnetic moments that are capable of being aligned in the direction of the applied field. They therefore have a positive (but small) susceptibility and a relative permeability slightly in excess of one. Paramagnetism occurs in all atoms and molecules with unpaired electrons; e.g. free atoms, free radicals, and compounds of transition metals containing ions with unfilled electron shells. It also occurs in metals as a result of the magnetic moments associated with the spins of the conducting electrons.

diamagnetism the magnetization is in the opposite direction to that of the applied field, i.e. the susceptibility is negative. Although all substances are diamagnetic, it is a weak form of magnetism and may be masked by other, stronger, forms. It results from changes induced in the orbits of electrons in the atoms of a substance by the applied field, the direction of the change (in accordance with Lenz's law) opposing the applied flux. There is thus a weak negative susceptibility and a relative permeability that is slightly less than one.

This wasn't mean to be snarky;p Just and espousing on magnetism. I like magnets.

This is one of four well-known Soft Gamma Repeaters (SGRs). These are neutron stars in or near our galaxy that produce intense blasts of X-ray and soft gamma-ray radiation. Normal neutron stars (e.g. the Crab pulsar) just put out a fairly steady pulsing signal.

It had been thought that SGRs are neutron stars with magnetic fields of ~1e14 Gauss (compared to the Crab's ~1e12 G or Earths ~1 G). This is a huge field that has enough energy (proportional to magnetic field squared) to power the huge blasts of radiation.

This new work by Samar Safi-Harb shows that the magnetic field is actually ~1e15 Gauss: 10x as strong and 100x the energy.

If there are any nearby planets with heavier elements and some range of chemistry, perhaps they could support life forms that derive their principal source of energy from such the magnetar's field.

This is an interesting thought. However, in this case, they (and the planet) would likely be boiled to vapour by the x- and gamma-ray bursts that let us know about the star's magnetic field in the first place.

Magnetic effects around gas giants, while far, far weaker, might still be strong enough to play a role in the evolution of any creatures on/in gas giant moons, though.

For a couple of interesting sci-fi books about life in and around neutron stars, check out "The Integral Trees"/"The Smoke Ring", by Larry Niven, and "Dragon's Egg", by Robert Forward.

During the explosion, a massive star dies and what remains is a compact stellar object that is composed entirely of neutrons -- the raw building blocks of matter.

Hmm, I never knew that neutrons were the raw building blocks of matter. Last I checked, they were just baryons (a class that also includes protons), and are themselves composed of constituent parts known as quarks (down and up quarks in this case).

This just goes to show the amount of science illiteracy that exists in our society. Even a journalist writing an article about a scientific discovery can't get basic concepts straight.

Hmm, I never knew that neutrons were the raw building blocks of matter. Last I checked, they were just baryons (a class that also includes protons), and are themselves composed of constituent parts known as quarks (down and up quarks in this case).

I can understand your need to nit pick, but actually, neutrons ARE raw building blocks of matter. Correct that they arent the ONLY raw building blocks of matter, but never the less they are a portion.

This just goes to show the amount of science illiteracy that exists in our society

how about conceptual illiteracy? An analogy was being used to describe the homogenous physical makup of this star, being neutrons, to identical blocks that compose it.

besides, for 90% of people reading this article, the information and analogy presented expresses the concept just fine.